Rollup of 5 pull requests

compiler/rustc_ast/src/visit.rs

@@ -268,8 +268,8 @@ pub trait Visitor<'ast>: Sized {
     fn visit_fn_ret_ty(&mut self, ret_ty: &'ast FnRetTy) -> Self::Result {
         walk_fn_ret_ty(self, ret_ty)
     }
-    fn visit_fn_header(&mut self, _header: &'ast FnHeader) -> Self::Result {
-        Self::Result::output()
+    fn visit_fn_header(&mut self, header: &'ast FnHeader) -> Self::Result {
+        walk_fn_header(self, header)
     }
     fn visit_expr_field(&mut self, f: &'ast ExprField) -> Self::Result {
         walk_expr_field(self, f)
@@ -292,6 +292,9 @@ pub trait Visitor<'ast>: Sized {
     fn visit_capture_by(&mut self, _capture_by: &'ast CaptureBy) -> Self::Result {
         Self::Result::output()
     }
+    fn visit_coroutine_kind(&mut self, _coroutine_kind: &'ast CoroutineKind) -> Self::Result {
+        Self::Result::output()
+    }
 }
 
 pub fn walk_crate<'a, V: Visitor<'a>>(visitor: &mut V, krate: &'a Crate) -> V::Result {
@@ -813,6 +816,12 @@ pub fn walk_fn_ret_ty<'a, V: Visitor<'a>>(visitor: &mut V, ret_ty: &'a FnRetTy)
     V::Result::output()
 }
 
+pub fn walk_fn_header<'a, V: Visitor<'a>>(visitor: &mut V, fn_header: &'a FnHeader) -> V::Result {
+    let FnHeader { safety: _, coroutine_kind, constness: _, ext: _ } = fn_header;
+    visit_opt!(visitor, visit_coroutine_kind, coroutine_kind.as_ref());
+    V::Result::output()
+}
+
 pub fn walk_fn_decl<'a, V: Visitor<'a>>(
     visitor: &mut V,
     FnDecl { inputs, output }: &'a FnDecl,
@@ -830,8 +839,9 @@ pub fn walk_fn<'a, V: Visitor<'a>>(visitor: &mut V, kind: FnKind<'a>) -> V::Resu
             try_visit!(walk_fn_decl(visitor, decl));
             visit_opt!(visitor, visit_block, body);
         }
-        FnKind::Closure(binder, _coroutine_kind, decl, body) => {
+        FnKind::Closure(binder, coroutine_kind, decl, body) => {
             try_visit!(visitor.visit_closure_binder(binder));
+            visit_opt!(visitor, visit_coroutine_kind, coroutine_kind.as_ref());
             try_visit!(walk_fn_decl(visitor, decl));
             try_visit!(visitor.visit_expr(body));
         }

compiler/rustc_ast_lowering/src/lib.rs

@@ -738,7 +738,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         allow_internal_unstable: Option<Lrc<[Symbol]>>,
     ) -> Span {
         self.tcx.with_stable_hashing_context(|hcx| {
-            span.mark_with_reason(allow_internal_unstable, reason, self.tcx.sess.edition(), hcx)
+            span.mark_with_reason(allow_internal_unstable, reason, span.edition(), hcx)
         })
     }
 

compiler/rustc_lint/src/early.rs

@@ -68,6 +68,10 @@ impl<'a, T: EarlyLintPass> EarlyContextAndPass<'a, T> {
 }
 
 impl<'a, T: EarlyLintPass> ast_visit::Visitor<'a> for EarlyContextAndPass<'a, T> {
+    fn visit_coroutine_kind(&mut self, coroutine_kind: &'a ast::CoroutineKind) -> Self::Result {
+        self.check_id(coroutine_kind.closure_id());
+    }
+
     fn visit_param(&mut self, param: &'a ast::Param) {
         self.with_lint_attrs(param.id, &param.attrs, |cx| {
             lint_callback!(cx, check_param, param);
@@ -111,17 +115,6 @@ impl<'a, T: EarlyLintPass> ast_visit::Visitor<'a> for EarlyContextAndPass<'a, T>
         self.with_lint_attrs(e.id, &e.attrs, |cx| {
             lint_callback!(cx, check_expr, e);
             ast_visit::walk_expr(cx, e);
-            // Explicitly check for lints associated with 'closure_id', since
-            // it does not have a corresponding AST node
-            match e.kind {
-                ast::ExprKind::Closure(box ast::Closure {
-                    coroutine_kind: Some(coroutine_kind),
-                    ..
-                }) => {
-                    cx.check_id(coroutine_kind.closure_id());
-                }
-                _ => {}
-            }
             lint_callback!(cx, check_expr_post, e);
         })
     }
@@ -156,14 +149,6 @@ impl<'a, T: EarlyLintPass> ast_visit::Visitor<'a> for EarlyContextAndPass<'a, T>
         lint_callback!(self, check_fn, fk, span, id);
         self.check_id(id);
         ast_visit::walk_fn(self, fk);
-
-        // Explicitly check for lints associated with 'closure_id', since
-        // it does not have a corresponding AST node
-        if let ast_visit::FnKind::Fn(_, _, sig, _, _, _) = fk {
-            if let Some(coroutine_kind) = sig.header.coroutine_kind {
-                self.check_id(coroutine_kind.closure_id());
-            }
-        }
     }
 
     fn visit_variant_data(&mut self, s: &'a ast::VariantData) {

compiler/rustc_lint/src/unused.rs

@@ -584,6 +584,7 @@ enum UnusedDelimsCtx {
     MatchScrutineeExpr,
     ReturnValue,
     BlockRetValue,
+    BreakValue,
     LetScrutineeExpr,
     ArrayLenExpr,
     AnonConst,
@@ -605,6 +606,7 @@ impl From<UnusedDelimsCtx> for &'static str {
             UnusedDelimsCtx::MatchScrutineeExpr => "`match` scrutinee expression",
             UnusedDelimsCtx::ReturnValue => "`return` value",
             UnusedDelimsCtx::BlockRetValue => "block return value",
+            UnusedDelimsCtx::BreakValue => "`break` value",
             UnusedDelimsCtx::LetScrutineeExpr => "`let` scrutinee expression",
             UnusedDelimsCtx::ArrayLenExpr | UnusedDelimsCtx::AnonConst => "const expression",
             UnusedDelimsCtx::MatchArmExpr => "match arm expression",
@@ -913,6 +915,10 @@ trait UnusedDelimLint {
                 (value, UnusedDelimsCtx::ReturnValue, false, Some(left), None, true)
             }
 
+            Break(_, Some(ref value)) => {
+                (value, UnusedDelimsCtx::BreakValue, false, None, None, true)
+            }
+
             Index(_, ref value, _) => (value, UnusedDelimsCtx::IndexExpr, false, None, None, false),
 
             Assign(_, ref value, _) | AssignOp(.., ref value) => {
@@ -1063,6 +1069,9 @@ impl UnusedDelimLint for UnusedParens {
                                 _,
                                 _,
                             ) if node.is_lazy()))
+                    && !((ctx == UnusedDelimsCtx::ReturnValue
+                        || ctx == UnusedDelimsCtx::BreakValue)
+                        && matches!(inner.kind, ast::ExprKind::Assign(_, _, _)))
                 {
                     self.emit_unused_delims_expr(cx, value, ctx, left_pos, right_pos, is_kw)
                 }

compiler/rustc_lint_defs/src/builtin.rs

@@ -4185,7 +4185,7 @@ declare_lint! {
     Warn,
     "never type fallback affecting unsafe function calls",
     @future_incompatible = FutureIncompatibleInfo {
-        reason: FutureIncompatibilityReason::FutureReleaseSemanticsChange,
+        reason: FutureIncompatibilityReason::EditionAndFutureReleaseSemanticsChange(Edition::Edition2024),
         reference: "issue #123748 <https://github.com/rust-lang/rust/issues/123748>",
     };
     @edition Edition2024 => Deny;
@@ -4239,7 +4239,7 @@ declare_lint! {
     Warn,
     "never type fallback affecting unsafe function calls",
     @future_incompatible = FutureIncompatibleInfo {
-        reason: FutureIncompatibilityReason::FutureReleaseErrorDontReportInDeps,
+        reason: FutureIncompatibilityReason::EditionAndFutureReleaseError(Edition::Edition2024),
         reference: "issue #123748 <https://github.com/rust-lang/rust/issues/123748>",
     };
     report_in_external_macro

compiler/rustc_lint_defs/src/lib.rs

@@ -381,6 +381,8 @@ pub enum FutureIncompatibilityReason {
     /// hard errors (and the lint removed). Preferably when there is some
     /// confidence that the number of impacted projects is very small (few
     /// should have a broken dependency in their dependency tree).
+    ///
+    /// [`EditionAndFutureReleaseError`]: FutureIncompatibilityReason::EditionAndFutureReleaseError
     FutureReleaseErrorReportInDeps,
     /// Code that changes meaning in some way in a
     /// future release.
@@ -419,6 +421,28 @@ pub enum FutureIncompatibilityReason {
     /// slightly changes the text of the diagnostic, but is otherwise the
     /// same.
     EditionSemanticsChange(Edition),
+    /// This will be an error in the provided edition *and* in a future
+    /// release.
+    ///
+    /// This variant a combination of [`FutureReleaseErrorDontReportInDeps`]
+    /// and [`EditionError`]. This is useful in rare cases when we
+    /// want to have "preview" of a breaking change in an edition, but do a
+    /// breaking change later on all editions anyway.
+    ///
+    /// [`EditionError`]: FutureIncompatibilityReason::EditionError
+    /// [`FutureReleaseErrorDontReportInDeps`]: FutureIncompatibilityReason::FutureReleaseErrorDontReportInDeps
+    EditionAndFutureReleaseError(Edition),
+    /// This will change meaning in the provided edition *and* in a future
+    /// release.
+    ///
+    /// This variant a combination of [`FutureReleaseSemanticsChange`]
+    /// and [`EditionSemanticsChange`]. This is useful in rare cases when we
+    /// want to have "preview" of a breaking change in an edition, but do a
+    /// breaking change later on all editions anyway.
+    ///
+    /// [`EditionSemanticsChange`]: FutureIncompatibilityReason::EditionSemanticsChange
+    /// [`FutureReleaseSemanticsChange`]: FutureIncompatibilityReason::FutureReleaseSemanticsChange
+    EditionAndFutureReleaseSemanticsChange(Edition),
     /// A custom reason.
     ///
     /// Choose this variant if the built-in text of the diagnostic of the
@@ -431,9 +455,15 @@ pub enum FutureIncompatibilityReason {
 impl FutureIncompatibilityReason {
     pub fn edition(self) -> Option<Edition> {
         match self {
-            Self::EditionError(e) => Some(e),
-            Self::EditionSemanticsChange(e) => Some(e),
-            _ => None,
+            Self::EditionError(e)
+            | Self::EditionSemanticsChange(e)
+            | Self::EditionAndFutureReleaseError(e)
+            | Self::EditionAndFutureReleaseSemanticsChange(e) => Some(e),
+
+            FutureIncompatibilityReason::FutureReleaseErrorDontReportInDeps
+            | FutureIncompatibilityReason::FutureReleaseErrorReportInDeps
+            | FutureIncompatibilityReason::FutureReleaseSemanticsChange
+            | FutureIncompatibilityReason::Custom(_) => None,
         }
     }
 }

compiler/rustc_middle/src/lint.rs

@@ -382,6 +382,17 @@ pub fn lint_level(
                 FutureIncompatibilityReason::EditionSemanticsChange(edition) => {
                     format!("this changes meaning in Rust {edition}")
                 }
+                FutureIncompatibilityReason::EditionAndFutureReleaseError(edition) => {
+                    format!(
+                        "this was previously accepted by the compiler but is being phased out; \
+                         it will become a hard error in Rust {edition} and in a future release in all editions!"
+                    )
+                }
+                FutureIncompatibilityReason::EditionAndFutureReleaseSemanticsChange(edition) => {
+                    format!(
+                        "this changes meaning in Rust {edition} and in a future release in all editions!"
+                    )
+                }
                 FutureIncompatibilityReason::Custom(reason) => reason.to_owned(),
             };
 

tests/ui/delegation/unsupported.rs

@@ -10,15 +10,11 @@ mod opaque {
     mod to_reuse {
         use super::Trait;
 
-        pub fn opaque_ret() -> impl Trait { unimplemented!() }
-        //~^ warn: this function depends on never type fallback being `()`
-        //~| warn: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+        pub fn opaque_ret() -> impl Trait { () }
     }
 
     trait ToReuse {
-        fn opaque_ret() -> impl Trait { unimplemented!() }
-        //~^ warn: this function depends on never type fallback being `()`
-        //~| warn: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+        fn opaque_ret() -> impl Trait { () }
     }
 
     // FIXME: Inherited `impl Trait`s create query cycles when used inside trait impls.

tests/ui/delegation/unsupported.stderr

@@ -1,74 +1,43 @@
-error[E0391]: cycle detected when computing type of `opaque::<impl at $DIR/unsupported.rs:25:5: 25:24>::{synthetic#0}`
-  --> $DIR/unsupported.rs:26:25
+error[E0391]: cycle detected when computing type of `opaque::<impl at $DIR/unsupported.rs:21:5: 21:24>::{synthetic#0}`
+  --> $DIR/unsupported.rs:22:25
    |
 LL |         reuse to_reuse::opaque_ret;
    |                         ^^^^^^^^^^
    |
 note: ...which requires comparing an impl and trait method signature, inferring any hidden `impl Trait` types in the process...
-  --> $DIR/unsupported.rs:26:25
+  --> $DIR/unsupported.rs:22:25
    |
 LL |         reuse to_reuse::opaque_ret;
    |                         ^^^^^^^^^^
-   = note: ...which again requires computing type of `opaque::<impl at $DIR/unsupported.rs:25:5: 25:24>::{synthetic#0}`, completing the cycle
-note: cycle used when checking that `opaque::<impl at $DIR/unsupported.rs:25:5: 25:24>` is well-formed
-  --> $DIR/unsupported.rs:25:5
+   = note: ...which again requires computing type of `opaque::<impl at $DIR/unsupported.rs:21:5: 21:24>::{synthetic#0}`, completing the cycle
+note: cycle used when checking that `opaque::<impl at $DIR/unsupported.rs:21:5: 21:24>` is well-formed
+  --> $DIR/unsupported.rs:21:5
    |
 LL |     impl ToReuse for u8 {
    |     ^^^^^^^^^^^^^^^^^^^
    = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
 
-warning: this function depends on never type fallback being `()`
-  --> $DIR/unsupported.rs:13:9
-   |
-LL |         pub fn opaque_ret() -> impl Trait { unimplemented!() }
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-   = note: for more information, see issue #123748 <https://github.com/rust-lang/rust/issues/123748>
-   = help: specify the types explicitly
-note: in edition 2024, the requirement `!: opaque::Trait` will fail
-  --> $DIR/unsupported.rs:13:32
-   |
-LL |         pub fn opaque_ret() -> impl Trait { unimplemented!() }
-   |                                ^^^^^^^^^^
-   = note: `#[warn(dependency_on_unit_never_type_fallback)]` on by default
-
-warning: this function depends on never type fallback being `()`
-  --> $DIR/unsupported.rs:19:9
-   |
-LL |         fn opaque_ret() -> impl Trait { unimplemented!() }
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-   = note: for more information, see issue #123748 <https://github.com/rust-lang/rust/issues/123748>
-   = help: specify the types explicitly
-note: in edition 2024, the requirement `!: opaque::Trait` will fail
-  --> $DIR/unsupported.rs:19:28
-   |
-LL |         fn opaque_ret() -> impl Trait { unimplemented!() }
-   |                            ^^^^^^^^^^
-
-error[E0391]: cycle detected when computing type of `opaque::<impl at $DIR/unsupported.rs:28:5: 28:25>::{synthetic#0}`
-  --> $DIR/unsupported.rs:29:24
+error[E0391]: cycle detected when computing type of `opaque::<impl at $DIR/unsupported.rs:24:5: 24:25>::{synthetic#0}`
+  --> $DIR/unsupported.rs:25:24
    |
 LL |         reuse ToReuse::opaque_ret;
    |                        ^^^^^^^^^^
    |
 note: ...which requires comparing an impl and trait method signature, inferring any hidden `impl Trait` types in the process...
-  --> $DIR/unsupported.rs:29:24
+  --> $DIR/unsupported.rs:25:24
    |
 LL |         reuse ToReuse::opaque_ret;
    |                        ^^^^^^^^^^
-   = note: ...which again requires computing type of `opaque::<impl at $DIR/unsupported.rs:28:5: 28:25>::{synthetic#0}`, completing the cycle
-note: cycle used when checking that `opaque::<impl at $DIR/unsupported.rs:28:5: 28:25>` is well-formed
-  --> $DIR/unsupported.rs:28:5
+   = note: ...which again requires computing type of `opaque::<impl at $DIR/unsupported.rs:24:5: 24:25>::{synthetic#0}`, completing the cycle
+note: cycle used when checking that `opaque::<impl at $DIR/unsupported.rs:24:5: 24:25>` is well-formed
+  --> $DIR/unsupported.rs:24:5
    |
 LL |     impl ToReuse for u16 {
    |     ^^^^^^^^^^^^^^^^^^^^
    = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
 
 error: recursive delegation is not supported yet
-  --> $DIR/unsupported.rs:42:22
+  --> $DIR/unsupported.rs:38:22
    |
 LL |         pub reuse to_reuse2::foo;
    |                              --- callee defined here
@@ -77,14 +46,14 @@ LL |     reuse to_reuse1::foo;
    |                      ^^^
 
 error[E0283]: type annotations needed
-  --> $DIR/unsupported.rs:52:18
+  --> $DIR/unsupported.rs:48:18
    |
 LL |     reuse Trait::foo;
    |                  ^^^ cannot infer type
    |
    = note: cannot satisfy `_: effects::Trait`
 
-error: aborting due to 4 previous errors; 2 warnings emitted
+error: aborting due to 4 previous errors
 
 Some errors have detailed explanations: E0283, E0391.
 For more information about an error, try `rustc --explain E0283`.

tests/ui/editions/never-type-fallback-breaking.e2021.fixed

@@ -16,7 +16,7 @@ fn main() {
 
 fn m() {
     //[e2021]~^ this function depends on never type fallback being `()`
-    //[e2021]~| this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //[e2021]~| this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
     let x: () = match true {
         true => Default::default(),
         //[e2024]~^ error: the trait bound `!: Default` is not satisfied
@@ -28,7 +28,7 @@ fn m() {
 
 fn q() -> Option<()> {
     //[e2021]~^ this function depends on never type fallback being `()`
-    //[e2021]~| this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //[e2021]~| this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
     fn deserialize<T: Default>() -> Option<T> {
         Some(T::default())
     }
@@ -45,7 +45,7 @@ fn help<'a: 'a, T: Into<()>, U>(_: U) -> Result<T, ()> {
 }
 fn meow() -> Result<(), ()> {
     //[e2021]~^ this function depends on never type fallback being `()`
-    //[e2021]~| this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //[e2021]~| this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
     help::<(), _>(1)?;
     //[e2024]~^ error: the trait bound `(): From<!>` is not satisfied
     Ok(())